For Real Madrid, it started so very well and ended so very badly. A goal after just 23 seconds gave them the lead against Barcelona and seemed to open the way for a shift in the balance of power. At 10.01, Madrid effectively had a six-point lead at the top of La Liga with a game in hand – a lead most considered unassailable. By the time the final whistle went just before midnight, the Santiago Bernabéu was already half-empty and Barcelona had long been in control. They were back on top too. Everything changes? Everything stays the same.

José Mourinho may take comfort from knowing that his side will go three points clear if they win next weekend while Barcelona are at the Club World Cup, but ultimately they were outclassed.

For all the recent doubts, Barcelona were once again wonderful. For all the recent improvements, Madrid were not good enough; now it is they who may be assailed by doubts. Mourinho's side had won 15 out of 15 but Barcelona are a different prospect. Mourinho has now faced them eight times and won only once.

Pep Guardiola put it kindly. "I am delighted with the performance," the Barcelona coach said. "Madrid will recover. There are no champions in December."

The game effectively ended with 25 minutes still remaining, when Barcelona got their third. Andrés Iniesta held off the challenges, Lionel Messi came in support and dropped a simple ball off to the right. Daniel Alves dashed up the wing, beyond tiring legs, into space, and delivered a cross of perfect precision for Cesc Fàbregas, sliding in and ducking towards the ball at the far post, prompting 25 minutes of Barcelona controlling the ball with ease.

Ninety minutes earlier, that had not seemed possible. A feature of Madrid's game this season, a key to that run, is that they have begun pressuring far higher, seeking teams out rather than waiting for them. The doubt was whether they would risk doing the same against Barcelona. They did. The first time Barcelona were forced back and the goalkeeper Víctor Valdés was hurried, his pass was perfectly placed; the second, it could hardly have been worse. Valdés played the ball straight to Angel di María. The Argentinian tried to find Karim Benzema, Sergio Busquets slid in to cut out the pass; Mesut Ozil went for goal, Busquets, recovering, slid in to cut it out again. This time, though, the ball squirmed through and lifted towards Benzema, lurking a few yards from goal, who volleyed in.

It was not just the goal. Madrid applied the pressure and Barcelona were uncomfortable, unable to maintain sustained possession. Messi, though, is always dangerous and when he took advantage of Sergio Ramos's slip, he dashed into the Madrid penalty area, stepped away from Pepe and took aim. Iker Casillas dived to push fractionally past his post. It was a warning. Messi appeared to tire of waiting for Barcelona, so he went looking for the ball himself on the half-hour. Dropping into his own half, he received a short pass from Gerard Piqué and set off on another run. Players were dragged towards him, first Ozil, then Lassana Diarra and Xabi Alonso, but Messi evaded them. As Diarra slid in, he slotted the ball through the gap for Alexis Sánchez who struck a clean, low finish beyond Casillas.

Suddenly, Barcelona looked a little more at ease. You had to admire their nerve. Alves was pushed higher on the right; Alexis sprinted across the front line; Iniesta, extraordinary, drifted left; Fàbregas drew closer to Xavi. Messi was everywhere. By half-time, Barcelona had wrested back something approaching their normal share of possession, while the intensity of Madrid's pressure lowered. Soon, it had gone entirely.

Barcelona took the lead within 10 minutes of the restart. A cross from the left was cut out, the ball looping towards Xavi five yards outside the penalty area. His volley caught Marcelo Vieira's heel and wrong-footed Casillas. The goalkeeper could not reach the ball, which squeezed in off the post.

Cristiano Ronaldo missed a good chance in the first half and then wasted an even better opportunity with the score at 2-1, when he headed wide from Xabi Alonso's cross. "Luck plays a part," Mourinho said ruefully.

Barcelona's third goal, a minute after Ronaldo's miss, ended it. Madrid had brief moments but their chance had gone.